Oscillator, electronic apparatus, and vehicle

ABSTRACT

A temperature-compensated oscillator includes a resonator element, an oscillating circuit, and a temperature compensation circuit, and in a case of varying temperature in a temperature range of ±5° C. centered on a reference temperature in intervals of 6 minutes, and assuming observation period as τ, a wander performance fulfills a condition that an MTIE value is equal to or shorter than 6 ns in a range of 0 s&lt;τ≦0.1 s, the MTIE value is equal to or shorter than 27 ns in a range of 0.1 s&lt;τ≦1 s, the MTIE value is equal to or shorter than 250 ns in a range of 1 s&lt;τ≦10 s, the MTIE value is equal to or shorter than 100 ns in a range of 10 s&lt;τ≦1700 s, and the MTIE value is equal to or shorter than 6332 ns in a range of 100 s&lt;τ≦1000 s.

BACKGROUND

1. Technical Field

The present invention relates to an oscillator, an electronic apparatus,and a vehicle.

2. Related Art

A temperature-compensated crystal oscillator (TCXO) has a quartz crystalresonator and an integrated circuit (IC) for oscillating the quartzcrystal resonator, wherein the IC compensates (performs temperaturecompensation on) the deviation (frequency deviation) from the desiredfrequency (nominal frequency) of the oscillation frequency of the quartzcrystal resonator in a predetermined temperature range, and thus, highfrequency accuracy can be obtained. Such a temperature-compensatedcrystal oscillator (TCXO) is disclosed in, for example, JP-A-2014-53663.

Further, the temperature-compensated crystal oscillator is high infrequency stability, and is therefore used for communication equipmentand so on for which high performance and high reliability are required.

The frequency signal (the oscillation signal) output from the oscillatorincludes phase fluctuation. Among the phase fluctuation of the frequencysignal, the fluctuation with a frequency lower than 10 Hz is calledwander. In ITU-T Recommendation G.813, there is defined the wanderperformance in the state in which the temperature is constant.

However, in the practical usage, it is difficult to make the oscillatoroperate under the environment in which the temperature is kept constant.For example, even if the oscillator is compliant with ITU-TRecommendation G.813, there is a possibility that sufficient performancecannot be exerted under a severe temperature environment such as thecase in which the oscillator is used for a car navigation system or avariety of vehicular gauges, and the case in which the oscillator isincorporated in a device, the temperature of which changes rapidly dueto the action of a fan or the like.

SUMMARY

An advantage of some aspects of the invention is to provide anoscillator available for an electronic apparatus and a vehicle for whichhigh frequency stability is required even under the severe temperatureenvironment. Another advantage of some aspects of the invention is toprovide an electronic apparatus and a vehicle each including theoscillator described above.

The invention can be implemented as the following forms or applicationexamples.

APPLICATION EXAMPLE 1

An oscillator according to this application example is atemperature-compensated oscillator including a resonator element, anoscillating circuit, and a temperature compensation circuit, wherein ina case of varying temperature in a temperature range of ±5° C. centeredon a reference temperature in intervals of 6minutes, and assumingobservation period as τ, a wander performance fulfills a condition thatan MTIE value is equal to and shorter than 6 ns in a range of 0 s<τ≦0.1s, the MTIE value is equal to and shorter than 27 ns in a range of 0.1s<τ≦1 s, the MTIE value is equal to and shorter than 250 ns in a rangeof 1 s<τ≦10 s, the MTIE value is equal to and shorter than 1700 ns in arange of 10 s<τ≦100 s, and the MTIE value is equal to and shorter than6300 ns in the range of 100 s<τ≦1000 s.

It is also possible to configure a variety of types of oscillationcircuit such as a pierce oscillator circuit, an inverter typeoscillation circuit, a Colpitts oscillator circuit, or a Hartleyoscillator circuit using the resonator element and the oscillatingcircuit.

In the oscillator according to this application example, in a case ofvarying temperature in a temperature range of ±5° C. centered on areference temperature in intervals of 6 minutes, and assumingobservation period as τ, the wander performance fulfills the conditionthat an MTIE value is equal to and shorter than 6 ns in a range of 0s<τ≦0.1 s, the MTIE value is equal to and shorter than 27 ns in a rangeof 0.1 s<τ≦1 s, the MTIE value is equal to and shorter than 250 ns in arange of 1 s<τ≦10 s, the MTIE value of equal to and shorter than 1700 nsin a range of 10 s<τ≦100 s, and the MTIE value is equal to and shorterthan 6300 ns in the range of 100 s<τ≦1000 s, and there is exerted thesuperior wander performance even in the environment in which thetemperature fluctuates. Therefore, the oscillator according to thisapplication example is also available for the electronic apparatus andthe vehicle for which high frequency stability is required even in asevere temperature environment.

APPLICATION EXAMPLE 2

In the oscillator according to the application example described above,in a case of keeping the temperature constant at the referencetemperature, the wander performance may fulfill a condition that theMTIE value is equal to or shorter than 15 ns in a range of 0.1 s<τ≦1 s,the MTIE value is equal to or shorter than 23 ns in a range of 1 s<τ≦10s, the MTIE value is equal to or shorter than 100 ns in a range of 10s<τ≦100 s, and the MTIE value is equal to or shorter than 700 ns in therange of 100 s<τ≦1000 s.

The oscillator according to this application example has such a superiorwander performance, compared to the related-art temperature-compensatedcrystal oscillator, as to fulfill, in a case of keeping the temperatureconstant at a reference temperature, the condition that the MTIE valueis equal to or shorter than 15 ns in the range of 0.1 s<τ≦1 s, the MTIEvalue is equal to or shorter than 23 ns in a range of 1 s<τ≦10 s, theMTIE value is equal to or shorter than 100 ns in a range of 10 s<τ≦100s, and the MTIE value is equal to or shorter than 700 ns in the range of100 s<τ≦1000 s. Therefore, the oscillator according to this applicationexample is also available for the electronic apparatus and the vehiclefor which high frequency stability is required.

APPLICATION EXAMPLE 3

In the oscillator according to the application example described above,the oscillator may further include a first container housing theresonator element, an electronic component provided with the oscillatingcircuit and the temperature-compensation circuit, and a second containerhousing the first container and the electronic component, and theelectronic component maybe bonded to the first container, a space may bedisposed between an inner surface of the second container and the firstcontainer, and a space may be disposed between an inner surface of thesecond container and the electronic component.

In the oscillator according to this application example, since theelectronic component is bonded to the first container, the space isdisposed between the inner surface of the second container and the firstcontainer, and the space is disposed between the inner surface of thesecond container and the electronic component, the heat generated in theelectronic component is conducted to the resonator element in a shortperiod of time to decrease the temperature difference between theelectronic component and the resonator element. As a result, the errorin temperature compensation by the temperature compensation circuitdecreases, and thus, the superior wander performance described above canbe realized.

APPLICATION EXAMPLE 4

In the oscillator according to the application example described above,the first container may include a base, and a lid adapted to seal thebase and made of metal, and the electronic component may bonded to thelid.

In the oscillator according to this application example, since thematerial of the lid to which the electronic component is bonded is metalhigh in thermal conductivity, the heat generated in the electroniccomponent is conducted to the resonator element in a short period oftime to decrease the temperature difference between the electroniccomponent and the resonator element. As a result, the error intemperature compensation by the temperature compensation circuitdecreases, and thus, the superior wander performance described above canbe realized.

APPLICATION EXAMPLE 5

In the oscillator according to the application example described above,the space in the second container may be in a vacuum state.

In the oscillator according to this application example, since the spacein the second container is in the vacuum state, it is possible to reducethe influence of the temperature fluctuation outside the secondcontainer on the electronic component and the resonator element.

APPLICATION EXAMPLE 6

An oscillator according to this application example is atemperature-compensated oscillator including a resonator element, anoscillating circuit, and a temperature compensation circuit, wherein ina case of keeping the temperature constant at a reference temperature,the wander performance fulfills the condition that the MTIE value isequal to or shorter than 15 ns in the range of 0.1 s<τ≦1 s, the MTIEvalue is equal to or shorter than 23 ns in a range of 1 s<τ≦10 s, theMTIE value is equal to or shorter than 100 ns in a range of 10 s<τ≦100s, and the MTIE value is equal to or shorter than 700 ns in the range of100 s<τ≦1000 s.

The oscillator according to this application example has such a superiorwander performance, compared to the related-art temperature-compensatedcrystal oscillator, as to fulfill, in a case of keeping the temperatureconstant at a reference temperature, the condition that the MTIE valueis equal to or shorter than 15 ns in the range of 0.1 s<τ≦1 s, the MTIEvalue is equal to or shorter than 23 ns in a range of 1 s<τ≦10 s, theMTIE value is equal to or shorter than 100 ns in a range of 10 s<τ≦100s, and the MTIE value is equal to or shorter than 700 ns in the range of100 s<τ≦1000 s. Therefore, the oscillator according to this applicationexample is also applicable for the electronic apparatus and the vehiclefor which high frequency stability is required.

APPLICATION EXAMPLE 7

An electronic apparatus according to this application example includesany one of the oscillators described above.

According to this application example, the electronic apparatus equippedwith the oscillator having the high frequency stability even in thesevere temperature environment can be realized.

APPLICATION EXAMPLE 8

A vehicle according to this application example includes any one of theoscillators described above.

According to this application example, the vehicle equipped with theoscillator having the high frequency stability even in the severetemperature environment can be realized.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 is a perspective view schematically showing an oscillatoraccording to an embodiment of the invention.

FIG. 2 is a cross-sectional view schematically showing the oscillatoraccording to the embodiment.

FIG. 3 is a plan view schematically showing the oscillator according tothe embodiment.

FIG. 4 is a bottom view schematically showing the oscillator accordingto the embodiment.

FIG. 5 is a plan view schematically showing a base of a package of theoscillator according to the embodiment.

FIG. 6 is a functional block diagram of the oscillator according to theembodiment.

FIG. 7 is a flowchart showing an example of a procedure of a method ofmanufacturing the oscillator according to the embodiment.

FIG. 8 is a diagram showing a measurement system for evaluating wanderperformance.

FIG. 9 is a cross-sectional view schematically showing the configurationof a comparative sample.

FIG. 10 is a graph showing a temperature profile in a chamber.

FIG. 11 is a graph showing a evaluation result of the wander performance(temperature fluctuation) of the oscillator according to the embodiment.

FIG. 12 is a graph showing a evaluation result of the wander performance(constant temperature) of the oscillator according to the embodiment.

FIG. 13 is a plan view schematically showing a base of a package of anoscillator according to a first modified example.

FIG. 14 is a functional block diagram showing an example of aconfiguration of an electronic apparatus according to the embodiment.

FIG. 15 is a diagram showing an example of an external view of theelectronic apparatus according to the embodiment.

FIG. 16 is a diagram showing an example of a vehicle according to theembodiment.

DESCRIPTION OF AN EXEMPLARY EMBODIMENT

A preferred embodiment of the invention will hereinafter be described indetail using the accompanying drawings. It should be noted that theembodiment described below does not unreasonably limit the contents ofthe invention as set forth in the appended claims. Further, all of theconstituents explained hereinafter are not necessarily essentialelements of the invention.

1. Oscillator 1.1. Configuration of Oscillator

FIG. 1 through FIG. 4 are diagrams schematically showing an example of astructure of an oscillator 1 according to the present embodiment. FIG. 1is a perspective view of the oscillator 1. FIG. 2 is a cross-sectionalview along the line II-II in FIG. 1. FIG. 3 is a top view of theoscillator 1. FIG. 4 is a bottom view of the oscillator 1. It should benoted that in FIG. 3, a lid 8 b is omitted from the drawing for the sakeof convenience.

As shown in FIG. 1 through FIG. 4, the oscillator 1 is configuredincluding an integrated circuit (IC) 2 as an electronic component, aresonator element 3, a package (a first container) 4, and a package (asecond container) 8.

The integrated circuit (IC) 2 is housed in the package 8. In the package8, the integrated circuit (IC) 2 is bonded (fixed) to the package 4 (alid 4 b) with a bonding member 9. As described later, the integratedcircuit (IC) 2 is configured including an oscillating circuit 10 and atemperature compensation circuit 40 (see FIG. 6).

As the resonator element 3, there can be used, for example, a quartzcrystal resonator element, a surface acoustic wave (SAW) resonatorelement, other piezoelectric resonator elements, or an MEMS (MicroElectro Mechanical Systems) resonator element. As a substrate materialof the resonator element 3, there can be used a piezoelectric materialsuch as a piezoelectric single crystal such as a quartz crystal, lithiumtantalate, or lithium niobate, or piezoelectric ceramics such as leadzirconate titanate, a silicon semiconductor material, or the like. As anexcitation unit of the resonator element 3, there can be used a deviceusing a piezoelectric effect, or electrostatic drive using Coulombforce.

The resonator element 3 has an excitation electrode 3 a and anexcitation electrode 3 b each made of metal and respectively disposed onthe obverse side and the reverse side of the resonator element 3, andoscillates with a desired frequency (a frequency required for theoscillator 1) corresponding to the mass of the resonator element 3including the excitation electrode 3 a and the excitation electrode 3 b.

The package 4 includes a base (package base) 4 a, and a lid 4 b sealingthe base 4 a. The package 4 houses the resonator element 3.Specifically, the base 4 a is provided with a recessed part, and therecessed part is covered with the lid 4 b to thereby house the resonatorelement 3. A space of the package 4 for housing the resonator element 3is provided with, for example, an inert gas atmosphere with, forexample, a nitrogen gas. The base 4 a is bonded (fixed) to a base 8 a ofthe package 8 with the bonding member 9 made of lysine or the like.

FIG. 5 is a plan view schematically showing the base 4 a of the package4.

As shown in FIG. 5, on the base 4 a, there are disposed electrode pads11 a, 11 b, electrode pads 13 a, 13 b, and extraction interconnections14 a, 14 b. It should be noted that in the case of the presentembodiment, the base 4 a is provided with a base main body shaped like aplate on which the electrode pads 11 a, 11 b are disposed, and a framebody surrounding the electrode pads 11 a, 11 b.

The electrode pads 11 a, 11 b are electrically connected respectively tothe two excitation electrodes 3 a, 3 b of the resonator element 3. Tothe electrode pads 11 a, 11 b, there is bonded (fixed) the resonatorelement 3 with a connection member 12 such as an electrically conductiveadhesive.

The electrode pads 13 a, 13 b are electrically connected respectively totwo external terminals (not shown) of the package 4. To the two externalterminals of the package 4, there are electrically connected twoterminals (an XO terminal and an XI terminal shown in FIG. 6 describedlater) of the integrated circuit (IC) 2, respectively.

The extraction interconnection 14 a electrically connects the electrodepad 11 a and the electrode pad 13 a to each other. The extractioninterconnection 14 b electrically connects the electrode pad 11 b andthe electrode pad 13 b to each other.

As shown in FIG. 2, the integrated circuit (IC) 2 is bonded (fixed) tothe lid 4 b with the bonding member 9. It is desirable for the bondingmember 9 to be, for example, an electrically conductive adhesive. Asshown in FIG. 3, the integrated circuit (IC) 2 and the package 4 (theresonator element 3) overlap each other in a planar view of theoscillator 1 viewed from the upper surface, and the integrated circuit(IC) 2 is directly mounted on the lid 4 b. As described above, in theoscillator 1, by bonding the integrated circuit (IC) 2 to the lid 4 b ofthe package 4 in which the resonator element 3 is housed, the integratedcircuit (IC) 2 and the resonator element 3 can be disposed adjacent toeach other. Thus, since the heat generated in the integrated circuit(IC) 2 is conducted to the resonator element 3 in a short period oftime, the temperature difference between the integrated circuit (IC) 2and the resonator element 3 can be made small.

The material of the base 4 a is not particularly limited, but a varietyof types of ceramics such as an aluminum oxide can be used therefor. Thematerial of the lid 4 b is, for example, metal. It is desirable for thematerial of the lid 4 b to be a material high in thermal conductivity,and there can be used, for example, nickel (Ni), cobalt (Co), and aniron alloy (e.g., Kovar). Further, it is also possible for the lid 4 bto be formed of a plate-like member coated with the metal high inthermal conductivity described above. It should be noted that thematerial of the plate-like member is not particularly limited. Since theheat generated in the integrated circuit (IC) 2 is conducted to theresonator element 3 in a short period of time by adopting the metal highin thermal conductivity as the material of the lid 4 b , the temperaturedifference between the integrated circuit (IC) 2 and the resonatorelement 3 can be made small. Further, for example, if at least a part ofa surface of the lid 4 b having contact with the bonding member 9 is ina coarse state (a coarse surface), the bonding state with the bondingmember 9 becomes good to thereby improve impact resistance and a heatexchanging performance. It should be noted that the coarse surface is inthe state of having unevenness formed by laser processing, and iscoarser compared to, for example, the surface on the housing space sideon which such processing is not performed.

It is also possible for the base 4 a to be provided with a metal bodyfor sealing disposed between the ceramic member and a seal-bonding partof the lid 4 b. The metal body can also be the frame body describedabove, or can also be disposed on a frame body made of ceramic, or canalso be a so-called seam ring made of, for example, a cobalt alloy forseam-sealing, or can also be what has a configuration of directlydisposing a metal film on the ceramic member.

In this case, since the metal film is easier to be reduced in thicknessthan the seam ring, the configuration of disposing the metal filmdirectly on the ceramic member can shorten the distance between the lid4 b and the ceramic member to thereby make it easier to transfer theheat, which transferred from the lid 4 b, to the ceramic member, namelythe resonator element 3, compared to the case of the seam ring.

Further, it is also possible for the lid 4 b to be warped so that theresonator element 3 side becomes in the convex state and the integratedcircuit (IC) 2 side becomes in the concave state in the state in whichthe lid 4 b is sealed with the base 4 a. If a concave region due to suchwarpage is located in an area overlapping the integrated circuit (IC) 2,it becomes easy to keep the bonding member 9 in the concave region.Further, due to the above, since sufficient amount of the bonding member9 can be disposed between the integrated circuit (IC) 2 and the lid 4 b,bonding between the integrated circuit (IC) 2 and the lid 4 b becomes ingood condition, and the heat exchanging performance between theintegrated circuit (IC) 2 and the lid 4 b and the base 4 a, namelybetween the integrated circuit (IC) 2 and the resonator element 3, isimproved.

Further, since the lid 4 b is convex toward the resonator element 3,there occurs the state in which the lid 4 b is located closer to theresonator element 3 compared to the case in which the lid 4 b iscompletely flat, and it becomes easy for the heat from the integratedcircuit (IC) 2 to be transferred to the resonator element 3 via the lid4 b.

It should be noted that as a method of warping the lid 4 b, there isprepared the lid 4 b which is, for example, flat in the state in whichthe lid 4 b is not fixed to the base 4 a, and then the lid 4 b and thebase 4 a are stacked on one another.

After stacking the lid 4 b and the base 4 a on one another, the lid 4 band the base 4 a are bonded to each other while heating the lid 4 b andthe base 4 a.

When thus heating the lid 4 b and the base 4 a, the temperature of thelid 4 b is lowered to a level lower than the temperature of the basemain body of the base 4 a, or the lid 4 b lower in thermal expansioncoefficient than the base main body is selected. Alternatively, it isalso possible to adopt both of them. Thus, since the lid 4 b contractsmore than the base 4 a when the lid 4 b and the base 4 a drop intemperature after sealing, the lid 4 b can easily be warped.

Further, by also warping the base 4 a convexly toward the opposite sideto the resonator element 3 side, it is possible to provide a large gapbetween the base main body and the package 8 described later to therebydegrade the heat exchanging performance between the base 4 a and thepackage 8. It should be noted that it is also possible to provide thebase main body constituting the gap with a pad electrode for mounting,and dispose a pad electrode for installation on a surface of the package8 opposed to the pad electrode for mounting, and then performsolder-bonding between the pad electrode for mounting and the padelectrode for installation. According also to such a configuration,since the solder increases in thickness as much as the increment of thegap compared to the case in which the base 4 a is flat, the heatexchanging performance between the base 4 a and the package 8 via thesolder degrades, and the oscillator 1 hard to be affected by disturbanceis obtained.

The package 8 includes a base (package base) 8 a, and a lid 8 b sealingthe base 8 a. The package 8 houses the package 4, in which the resonatorelement 3 is housed, and the integrated circuit (IC) 2 in the samespace. Specifically, the base 8 a is provided with a recessed part, andthe recessed part is covered with the lid 8 b to thereby house theintegrated circuit (IC) 2 and the package 4. A space of the package 8for housing the integrated circuit (IC) 2 and the package 4 is providedwith, for example, an inert gas atmosphere with, for example, a nitrogengas.

Between the inner surface of the package 8 and the package 4, there isdisposed a space. In the example shown in the drawings, the inner wallsurface of the base 8 a and the package 4 do not have contact with eachother, and a space (gap) is disposed therebetween. Further, the lid 8 band the package 4 do not have contact with each other, and a space (gap)is disposed therebetween.

Between the inner surface of the package 8 and the integrated circuit(IC) 2, there is disposed a space. In the example shown in the drawings,the inner wall surface of the base 8 a and the integrated circuit (IC) 2do not have contact with each other, and a space (gap) is disposedtherebetween. Further, the lid 8 b and the integrated circuit (IC) 2 donot have contact with each other, and a space (gap) is disposedtherebetween.

The material of the base 8 a is not particularly limited, but a varietyof types of ceramics such as an aluminum oxide can be used therefor. Thematerial of the lid 8 b is, for example, metal. The lid 8 b of thepresent embodiment has a plate-like shape (flat shape), and is smallerin area compared to the cap-like shape provided with a recess.Therefore, since it is easy to ward off the wind from the lateraldirection of the package, it is possible to prevent the temperaturevariation due to the outside air. It should be noted that a seal-bondingmember is disposed for bonding the base 8 a made of ceramic and the lid8 b. The seal-bonding member is a metal seal-bonding member including amaterial such as a cobalt alloy or Au, or a nonmetal seal-bonding membersuch as glass or resin.

In the oscillator 1, the distance Dl between the lid 8 b of the package8 and the integrated circuit (IC) 2 is longer than the distance D2between the integrated circuit (IC) 2 and the resonator element 3. Inthe example shown in the drawings, the distance D1 is the distancebetween the lower surface of the lid 8 b and the upper surface of theintegrated circuit (IC) 2, and the distance D2 is the distance betweenthe lower surface of the integrated circuit (IC) 2 and the upper surfaceof the resonator element 3. As described above, by locating theintegrated circuit (IC) 2 closer to the resonator element 3 than the lid8 b, the temperature difference between the integrated circuit (IC) 2and the resonator element 3 can be decreased.

On the surfaces of the inside or the recessed part of the base 8 a,there are disposed interconnections not shown for electricallyconnecting two terminals (the XO terminal and the XI terminal shown inFIG. 6 described later) of the integrated circuit (IC) 2 and twoterminals (the excitation electrode 3 a and the excitation electrode 3b) of the resonator element 3 respectively to each other. Further, onthe surfaces of the inside or the recessed part of the base 8 a, thereare disposed interconnections not shown electrically connected to therespective external terminals 6, and the interconnections and theterminals of the integrated circuit (IC) 2 are respectively bonded toeach other with respective bonding wires 7 made of gold or the like.

It should be noted that, for example, if at least a part of a surface ofthe integrated circuit (IC) 2 having contact with the bonding member 9is in a coarse state (a coarse surface), the bonding state with thebonding member 9 becomes good to thereby improve the impact resistanceand the heat exchanging performance. It should be noted that the coarsesurface is a surface in the state of having asperity shaped like streaksor the like formed by, for example, cutting work.

As shown in FIG. 4, the oscillator 1 is provided with four externalterminals 6, namely an external terminal VDD1 as a power supplyterminal, an external terminal VSS1 as a ground terminal, an externalterminal VC1 as a terminal to which a signal for controlling thefrequency is input, and an external terminal OUT1 as an output terminal,disposed on the bottom surface (a reverse surface of the base 8 a). Theexternal terminal VDD1 is supplied with the power supply voltage, andthe external terminal VSS1 is grounded.

FIG. 6 is a functional block diagram of the oscillator 1. As shown inFIG. 6, the oscillator 1 is an oscillator including the resonatorelement 3, and the integrated circuit (IC) 2 for oscillating theresonator element 3.

The integrated circuit (IC) 2 is provided with a VDD terminal as a powersupply terminal, a VSS terminal as a ground terminal, an OUT terminal asan output terminal, a VC terminal as a terminal to which a signal forcontrolling the frequency is input, and the XI terminal and the XOterminal as connection terminals with the resonator element 3. The VDDterminal, the VSS terminal, the OUT terminal, and the VC terminal areexposed on the surface of the integrated circuit (IC) 2, and areconnected respectively to the external terminals VDD1, VSS1, OUT1, andVC1 provided to the package 8. Further, the XI terminal is connected toone end (one terminal) of the resonator element 3, and the XO terminalis connected to the other end (the other terminal) of the resonatorelement 3.

In the present embodiment, the integrated circuit (IC) 2 is configuredincluding an oscillating circuit 10, an output circuit 20, a frequencyadjustment circuit 30, an automatic frequency control (AFC) circuit 32,a temperature compensation circuit 40, a temperature sensor 50, aregulator circuit 60, a storage 70, and a serial interface (I/F) circuit80. It should be noted that the integrated circuit (IC) 2 can have aconfiguration obtained by eliminating or modifying some of theseconstituents, or adding other constituents.

The regulator circuit 60 generates a constant voltage to be a powersupply voltage or a reference voltage of some or all of the oscillatingcircuit 10, the frequency adjustment circuit 30, the AFC circuit 32, thetemperature compensation circuit 40, and the output circuit 20 based onthe power supply voltage VDD (positive voltage) supplied from the VDDterminal.

The storage 70 has a nonvolatile memory 72 and a register 74, and isconfigured so that reading from and writing to the nonvolatile memory 72or the register 74 can be performed from the external terminals via theserial interface circuit 80. In the present embodiment, since theintegrated circuit (IC) 2 has only four terminals to be connected to theexternal terminals of the oscillator 1, namely the VDD terminal, the VSSterminal, the OUT terminal, and the VC terminal, for example, when thevoltage of the VDD terminal is higher than a threshold value, the serialinterface circuit 80 accepts a clock signal input from the VC terminaland a data signal input from the OUT terminal, and then performsreading/writing of the data from/to the nonvolatile memory 72 or theregister 74.

The nonvolatile memory 72 is a storage for storing a variety of controldata, and can be a variety of types of rewritable nonvolatile memorysuch as an electrically erasable programmable read-only memory (EEPROM)or a flash memory, or can also be a variety of types of non-rewritablenonvolatile memory such as a one-time programmable read-only memory(one-time PROM).

The nonvolatile memory 72 stores frequency adjustment data forcontrolling the frequency adjustment circuit 30, and temperaturecompensation data (first-order compensation data, . . . , n-th-ordercompensation data) for controlling the temperature compensation circuit40. Further, the nonvolatile memory 72 also stores data (not shown) forrespectively controlling the output circuit 20 and the AFC circuit 32.

The frequency adjustment data is the data for adjusting the frequency ofthe oscillator 1, and in the case in which the frequency of theoscillator 1 is shifted from the desired frequency, it is possible tofinely adjust the frequency of the oscillator 1 so as to come closer tothe desired frequency by rewriting the frequency adjustment data.

The temperature compensation data (the first-order compensation data,the n-th-order compensation data) are the data for compensating thefrequency-temperature characteristic of the oscillator 1 and calculatedin a temperature compensation adjustment process of the oscillator 1,and can also be, for example, first-order through n-th-order coefficientvalues corresponding to the respective order components of the frequencytemperature characteristic of the resonator element 3. Here, as thehighest order n of the temperature compensation data, there is selecteda value with which the frequency-temperature characteristic of theresonator element 3 is canceled out, and an influence of the temperaturecharacteristic of the integrated circuit (IC) 2 can also be corrected.For example, the value n can also be an integer value greater than aprincipal order of the frequency-temperature characteristic of theresonator element 3. For example, if the resonator element 3 is anAT-cut quartz crystal resonator element, the frequency-temperaturecharacteristic exhibits a cubic curve, and since the principal orderthereof is three, an integer value (e.g., five or six) greater thanthree can also be selected as the value n. It should be noted that thetemperature compensation data can include all of the first-order throughn-th-order compensation data, or some of the first-order throughn-th-order compensation data.

Each of the data stored in the nonvolatile memory 72 is transferred fromthe nonvolatile memory 72 to the register 74 when powering on (when thevoltage of the VDD terminal rises from 0 V to a desired voltage) theintegrated circuit (IC) 2, and is then held in the register 74. Then,the frequency adjustment data to be held in the register 74 is input tothe frequency adjustment circuit 30, the temperature compensation data(the first-order compensation data, . . . , the n-th-order compensationdata) to be held in the register 74 are input to the temperaturecompensation circuit 40, and the data for the control to be held in theregister 74 are also input to the output circuit 20 and the AFC circuit32.

In the case in which the nonvolatile memory 72 is non-rewritable, thedata are directly written into the respective bits of the register 74,which holds the data transferred from the nonvolatile memory 72, fromthe external terminals via the serial interface circuit 80, thenadjusted/selected so that the oscillator 1 fulfills the desiredcharacteristic, and then each of the data thus adjusted/selected isfinally written into the nonvolatile memory 72 when inspecting theoscillator 1. Further, in the case in which the nonvolatile memory 72 isrewritable, it is also possible to arrange that each of the data iswritten into the nonvolatile memory 72 from the external terminals viathe serial interface circuit 80 when inspecting the oscillator 1. Itshould be noted that since writing to the nonvolatile memory 72generally takes time, when inspecting the oscillator 1, in order toshorten the inspection time, it is also possible to arrange that thedata are directly written into the respective bits of the register 74from the external terminals via the serial interface circuit 80, andthen each of the data adjusted/selected is finally written into thenonvolatile memory 72.

The oscillating circuit 10 amplifies the output signal of the resonatorelement 3 to feed back the result to the resonator element 3 to therebyoscillate the resonator element 3, and then outputs an oscillationsignal based on the oscillation of the resonator element 3. For example,the oscillation stage current of the oscillating circuit 10 can becontrolled by the control data held in the register 74.

The frequency adjustment circuit 30 generates the voltage correspondingto the frequency adjustment data held in the register 74, and thenapplies the voltage to an end of a variable capacitance element (notshown) functioning as a load capacitance of the oscillating circuit 10.Thus, the oscillation frequency (the reference frequency) of theoscillating circuit 10 at predetermined temperature (e.g., 25° C.) andunder the condition in which the voltage of the VC terminal becomes apredetermined voltage (e.g., VDD/2) is controlled (finely adjusted) soas to become roughly the desired frequency.

The AFC circuit 32 generates the voltage corresponding to the voltage ofthe VC terminal, and then applies the voltage to an end of a variablecapacitance element (not shown) functioning as a load capacitance of theoscillating circuit 10. Thus, the oscillation frequency (the oscillationfrequency of the resonator element 3) of the oscillating circuit 10 iscontrolled based on the voltage value of the VC terminal. For example,the gain of the AFC circuit 32 can also be controlled by the controldata held in the register 74.

The temperature sensor 50 is a thermosensor for outputting a signal(e.g., a voltage corresponding to the temperature) corresponding to theambient temperature of the thermosensor. The temperature sensor 50 canbe a positive type, in which the higher the temperature is, the higherthe output voltage is, or can also be a negative type, in which thehigher the temperature is, the lower the output voltage is. It should benoted that a device, the output voltage of which varies as linearly aspossible with respect to the change in temperature in a desiredtemperature range in which the operation of the oscillator 1 isguaranteed, is desirable as the temperature sensor 50.

An output signal from the temperature sensor 50 is input to thetemperature compensation circuit 40, and the temperature compensationcircuit 40 generates the voltage (temperature compensation voltage) forcompensating the frequency-temperature characteristic of the resonatorelement 3, and then applies the voltage to an end of a variablecapacitance element (not shown) functioning as a load capacitance of theoscillating circuit 10. Thus, the oscillation frequency of theoscillating circuit 10 is controlled so as to be roughly constantirrespective of the temperature. In the present embodiment, thetemperature compensation circuit 40 is configured including afirst-order voltage generation circuit 41-1 through an n-th-ordervoltage generation circuit 41-n , and an adder circuit 42.

The output signal from the temperature sensor 50 is input to each of thefirst-order voltage generation circuit 41-1 through the n-th-ordervoltage generation circuit 41-n, and the first-order voltage generationcircuit 41-1 through the n-th-order voltage generation circuit 41-ngenerate a first-order compensation voltage through an n-th-ordercompensation voltage for compensating the first-order component throughthe n-th-order component of the frequency-temperature characteristic inaccordance with the first-order compensation data through the n-th-ordercompensation data held in the register 74, respectively.

The adder circuit 42 adds the first-order compensation voltage throughthe n-th-order compensation voltage respectively generated by thefirst-order voltage generation circuit 41-1 through the n-th-ordervoltage generation circuit 41-n to each other, and then outputs theresult. The output voltage of the adder circuit 42 becomes the outputvoltage (the temperature compensation voltage) of the temperaturecompensation circuit 40.

The oscillation signal output by the oscillating circuit 10 is input tothe output circuit 20, and the output circuit 20 generates anoscillation signal for external output, and then outputs the oscillationsignal to the outside via the OUT terminal. For example, the divisionratio and the output level of the oscillation signal in the outputcircuit 20 can be controlled by the control data held in the register74. The output frequency range of the oscillator 1 is, for example, nolower than 10 MHz and no higher than 800 MHz.

The oscillator 1 configured as described above functions as avoltage-controlled temperature-compensated oscillator (avoltage-controlled temperature-compensated crystal oscillator (VC-TCXO)if the resonator element 3 is a quartz crystal resonator element) foroutputting the oscillation signal with a constant frequencycorresponding to the voltage of the external terminal VC1 in a desiredtemperature range irrespective of the temperature.

1.2. Method of Manufacturing Oscillator

FIG. 7 is a flowchart showing an example of a procedure of a method ofmanufacturing the oscillator 1 according to the present embodiment. Itis also possible to eliminate or modify some of the processes S10through S70 shown in FIG. 7, or add other processes. Further, it ispossible to arbitrarily change the order of the processes to the extentpossible.

In the example shown in FIG. 7, firstly, the integrated circuit (IC) 2and the resonator element 3 (the package 4 housing the resonator element3) are mounted (S10) on the package 8 (the base 8 a). Due to the processS10, the integrated circuit (IC) 2 and the resonator element 3 areconnected to each other with interconnections disposed on the surfacesof the inside or the recessed part of the base 8 a to achieve the statein which the integrated circuit (IC) 2 and the resonator element 3 areelectrically connected to each other when supplying the integratedcircuit (IC) 2 with the electrical power.

Then, the base 8 a is sealed with the lid 8 b, and then a thermaltreatment is performed to bond (S20) the lid 8 b to the base 8 a. Due tothe process S20, assembling of the oscillator 1 is completed.

Then, the reference frequency (the frequency at the referencetemperature T0 (e.g., 25° C.)) of the oscillator 1 is adjusted (S30). Inthis process S30, the oscillator 1 is oscillated at the referencetemperature T0 to measure the frequency, and then the frequencyadjustment data is determined so that the frequency deviation comescloser to zero.

Then, the VC sensitivity of the oscillator 1 is adjusted (S40). In thisprocess S40, the oscillator 1 is oscillated to measure the frequency inthe state of applying a predetermined voltage (e.g., 0 V or VDD) to theexternal terminal VC1 at the reference temperature T0, and then theadjustment data of the AFC circuit 32 is determined so that the desiredVC sensitivity can be obtained.

Then, the temperature compensation adjustment of the oscillator 1 isperformed (S50). In this temperature compensation adjustment processS50, the frequency of the oscillator 1 is measured at a plurality oftemperature points in the desired temperature range (e.g., no lower than−40° C. and no higher than 85° C.), and the temperature compensationdata (the first-order compensation data, . . . , the n-th-ordercompensation data) for correcting the frequency-temperaturecharacteristic of the oscillator 1 are generated based on themeasurement result. Specifically, a calculation program for thetemperature compensation data approximates the frequency-temperaturecharacteristic (including the frequency-temperature characteristic ofthe resonator element 3 and the temperature characteristic of theintegrated circuit (IC) 2) of the oscillator 1 by an n-th-order formulawith the temperature (an output voltage of the temperature sensor 50) asa variable using the measurement result of the frequency at theplurality of temperature points, and then generates the temperaturecompensation data (the first-order compensation data, the n-th-ordercompensation data) corresponding to the approximation formula. Forexample, the calculation program for the temperature compensation datagenerates such temperature compensation data (the first-ordercompensation data, the n-th-order compensation data) as to vanish thefrequency deviation at the reference temperature T0, and decrease thewidth of the frequency deviation in the desired temperature range.

Then, the data respectively obtained in the processes S30, S40, and S50are stored (S60) in the nonvolatile memory 72 of the storage 70.

Finally, the frequency-temperature characteristic of the oscillator 1 ismeasured to determine (S70) whether or not the oscillator 1 isdefective. In this process S70, the frequency of the oscillator 1 ismeasured while gradually changing the temperature to evaluate whether ornot the frequency deviation is within a predetermined range in thedesired temperature range (e.g., no lower than −40° C. and no higherthan 85° C.), and if the frequency deviation is within the predeterminedrange, it is determined that the oscillator 1 is a non-defectiveproduct, or if the frequency deviation is not within the predeterminedrange, it is determined that the oscillator 1 is a defective product.

1.3. Wander Performance of Oscillator

The wander denotes the fluctuation with a frequency lower than 10 Hzamong the phase fluctuation of the frequency signal (oscillation signal)output from the oscillator. The wander performance is defined as maximumtime interval error (MTIE). The MTIE denotes the maximum value of apeak-to-peak value of the phase fluctuation value in an observationperiod τ when dividing the observation result of the phase fluctuationvalue with respect to the reference clock into observation periods τ. Inother words, the maximum value of the peak-to-peak value of the phasefluctuation value with respect to the reference clock in the observationperiod τ becomes the MTIE value in the observation period τ.

FIG. 8 is a diagram showing a measurement system 100 for evaluating (formeasuring the MTIE value) the wander performance of the oscillator 1.

As shown in FIG. 8, the measurement system 100 includes the oscillator1, a power supply 102, a chamber 104, a reference signal generator 106,a function generator 108, an interval counter 110, and a personalcomputer (PC) 112.

The configuration of the oscillator 1 used for the present evaluation isas explained in “1.1. Configuration of Oscillator” (see FIG. 1 throughFIG. 4) described above. It should be noted that the space of thepackage 4, in which the resonator element 3 is housed, and the space ofthe package 8, in which the integrated circuit (IC) 2 and the package 4are housed, are each provided with a nitrogen gas atmosphere. Further,the resonator element 3 is a quartz crystal resonator element. Theoscillator 1 is supplied with the power supply voltage Vcc=3.3 V fromthe poser supply 102. The output frequency (the nominal frequency) ofthe oscillator 1 was set to 19.2 MHz. The oscillator 1 is a CMOS outputtype, and the capacitance load was set to 15 pF.

The oscillator 1 is housed in the chamber 104, the temperature of whichcan be controlled. The temperature in the chamber 104 is controlled bythe PC 112.

In the measurement system 100, the reference signal (reference clock)can be obtained by generating the frequency signal of 19.2 MHz identicalto the output frequency of the oscillator 1 using the function generator108 from the frequency signal of 10 MHz output by the reference signalgenerator 106.

The measurement target signal (the frequency signal of the oscillator 1)and the reference signal are input to the interval counter 110. In theinterval counter 110, the phase fluctuation value of the measurementtarget signal with respect to the reference signal is measured, andthen, the MTIE value is calculated in the PC 112 from the measurementresult.

It should be noted that a related-art temperature-compensated crystaloscillator (a comparative sample C1) was prepared as a comparativeexample, and the evaluation of the wander performance was performedsimilarly on the comparative sample C1.

FIG. 9 is a cross-sectional view schematically showing a configurationof the comparative sample C1.

In the comparative sample C1, as shown in FIG. 9, the base 8 a has anH-shaped structure, two principal surfaces of which are each providedwith a recessed part. In the comparative sample C1, the resonatorelement 3 is housed in the recessed part provided to one of theprincipal surfaces of the base 8 a, and the integrated circuit (IC) 2 ishoused in the recessed part provided to the other of the principalsurfaces. It should be noted that the rest of the configuration of thecomparative sample C1 is substantially the same as that of theoscillator 1.

1.3.1. Wander Performance When Varying Temperature

Firstly, the wander performance of the oscillator 1 in the case ofvarying the temperature in the chamber 104 was evaluated using themeasurement system 100 shown in FIG. 8.

FIG. 10 is a graph showing a temperature profile in the chamber 104. Itshould be noted that the horizontal axis of the graph shown in FIG. 10represents time (minutes), and the vertical axis represents thetemperature in the chamber 104.

Here, in the measurement system 100, the measurement of the MTIE valueof the oscillator 1 was performed while varying the temperature in thechamber 104 with the temperature profile shown in FIG. 10. Specifically,as shown in FIG. 10, the temperature in the chamber 104 was varied inthe temperature range of ±5° C. centered on the reference temperature T0(25° C.) in the intervals of 6 minutes. More specifically, it wasrepeated that the temperature of the chamber 104 was linearly raised for3 minutes from 20° C. to 30° C. and then linearly dropped for 3 minutesfrom 30° C. to 20° C.

It should be noted that the similar measurement was performed also onthe comparative sample Cl.

FIG. 11 is a graph showing the evaluation result (measurement result ofthe MTIE value) of the wander performance of the oscillator 1 and thecomparative sample C1 in the case in which the temperature was varied inthe temperature range of ±5° C. centered on the reference temperature T0(25° C.) in the intervals of 6 minutes. The horizontal axis of the graphshown in FIG. 11 represents the observation period (tau) τ (second), andthe vertical axis represents the MTIE value (10⁻⁹ second).

Table 1 described below is a table showing the MTIE value of theoscillator 1 and the comparative sample C1 at τ=0.1 s (second), τ=1 s,τ=10 s, τ=100 s, and τ=1000 s.

TABLE 1 MTIE value [ns] of MTIE value [ns] of τ [s] oscillator 1comparative sample C1 0.1 6 13 1 27 37 10 246 351 100 1678 2704 10006332 12520

As shown in FIG. 11 and Table 1, in the oscillator 1, in the case ofvarying the temperature in the temperature range of ±5° C. centered onthe reference temperature T0 (25° C.) in the intervals of 6 minutes, thewander performance fulfills the condition that the MTIE value is equalto or shorter than 6 ns (nanoseconds) in a range of 0 s<τ≦0.1 s, theMTIE value is equal to or shorter than 27 ns in a range of 0.1 s<τ≦1 s,the MTIE value is equal to or shorter than 250 ns in a range of 1 s<τ≦10s, the MTIE value is equal to or shorter than 1700 ns in a range of 10s<τ≦100 s, and the MTIE value is equal to or shorter than 6300 ns in arange of 100 s<τ≦1000 s. As described above, the oscillator 1 has asuperior wander performance compared to the comparative sample C1.

1.3.2. Wander Performance When Keeping Temperature Constant at ReferenceTemperature

Then, the wander performance of the oscillator 1 in the case of keepingthe temperature in the chamber 104 constant at the reference temperatureT0 (25° C.) was evaluated using the measurement system 100 shown in FIG.8.

Here, in the measurement system 100, the measurement of the MTIE valueof the oscillator 1 was performed while keeping the temperature in thechamber 104 constant at the reference temperature T0 (25° C.).

It should be noted that the similar measurement was performed also onthe comparative sample C1.

FIG. 12 is a graph showing the evaluation result (measurement result ofthe MTIE value) of the wander performance of the oscillator 1 and thecomparative sample C1 in the case in which the temperature in thechamber 104 was kept constant at the reference temperature T0 (25° C.).The horizontal axis of the graph shown in FIG. 12 represents theobservation period τ (second), and the vertical axis represents the MTIEvalue (10⁻⁹ second).

Table 2 described below is a table showing the MTIE value of theoscillator 1 and the comparative sample C1 at τ=0.1 s, τ=1 s, τ=10 s,τ=100 s, and τ=1000 s.

TABLE 2 MTIE value [ns] of MTIE value [ns] of τ [s] oscillator 1comparative sample C1 0.1 13 29 1 15 35 10 23 83 100 100 520 1000 6564825

As shown in FIG. 12 and Table 2, in the oscillator 1, in the case ofkeeping the temperature constant at the reference temperature T0 (25°C.), the wander performance fulfills the condition that the MTIE valueis equal to or shorter than 15 ns in the range of 0.1 s<τ≦1 s, the MTIEvalue is equal to or shorter than 23 ns in the range of 1 s<τ≦10 s, theMTIE value is equal to or shorter than 100 ns in the range of 10 s<τ≦100s, and the MTIE value is equal to or shorter than 700 ns in the range of100 s<τ≦1000 s. As described above, the oscillator 1 has a superiorwander performance compared to the comparative sample Cl even by takingonly the condition of the constant temperature.

The oscillator 1 according to the present embodiment has, for example,the following features.

In the oscillator 1, in the case of varying the temperature in thetemperature range of ±5° C. centered on the reference temperature T0(25° C.) in the intervals of 6 minutes, the wander performance fulfillsthe condition that the MTIE value is equal to or shorter than 6 ns inthe range of 0 s<τ≦0.1 s, the MTIE value is equal to or shorter than 27ns in the range of 0.1 s<τ≦1 s, the MTIE value is equal to or shorterthan 250 ns in the range of 1 s<τ≦10 s, the MTIE value is equal to orshorter than 1700 ns in the range of 10 s<τ≦100 s, and the MTIE value isequal to or shorter than 6300 ns in the range of 100 s<τ≦1000 s.

Here, in ITU-T Recommendation G.813, there is defined the wanderperformance in the state in which the temperature is constant. In theoscillator 1, the wander performance in the case of varying thetemperature fulfills the wander performance in the state in which thetemperature is constant as defined in ITU-T Recommendation G.813 in arange of 0 s<τ≦100 s. Further, also in the range of 100 s<τ≦1000 s,there can be obtained the wander performance equivalent to the wanderperformance thus defined although inferior to the wander performancethus defined. As described above, in the oscillator 1, there is exertedthe superior wander performance even in the environment in which thetemperature fluctuates. Therefore, the oscillator 1 is also availablefor the electronic apparatus and the vehicle for which high frequencystability is required even in the severe temperature environment.

In the oscillator 1, in the case of keeping the temperature constant atthe reference temperature T0, the wander performance fulfills thecondition that the MTIE value is equal to or shorter than 15 ns in therange of 0.1 s<τ≦1 s, the MTIE value is equal to or shorter than 23 nsin the range of 1 s<τ≦10 s, the MTIE value is equal to or shorter than100 ns in the range of 10 s<τ≦100 s, and the MTIE value is equal to orshorter than 700 ns in the range of 100 s<τ≦1000 s. The wanderperformance of the oscillator 1 sufficiently fulfills the wanderperformance defined in ITU-T Recommendation G.813, and the oscillator 1has the excellent wander performance.

Further, in the oscillator 1, the difference between the wanderperformance in the case of varying the temperature and the wanderperformance in the case of keeping the temperature constant is smallercompared to the related-art temperature-compensated crystal oscillator(the comparative sample C1). In other words, it can be said that in theoscillator 1, the deterioration of the wander performance is small evenin the severe temperature environment.

As described above, since the oscillator 1 has the superior wanderperformance even in the severe temperature environment compared to therelated-art temperature-compensated crystal oscillator (the comparativesample C1), by using the oscillator 1 for, for example, a communicationapparatus as described below, it is possible to realize thecommunication apparatus having excellent communication performance evenin the severe temperature environment. Further, it is possible to applythe oscillator 1 to the electronic apparatus and the vehicle, for whichsuch high frequency stability is required that, for example, theoven-controlled crystal oscillator (OCXO) is used. As a result,down-sizing and power saving of the electronic apparatus and the vehicleare achievable.

The oscillator 1 includes the package 4 housing the resonator element 3,the integrated circuit (IC) 2 provided with the oscillating circuit 10and the temperature compensation circuit 40, and the package 8 housingthe package 4 and the integrated circuit (IC) 2, and the integratedcircuit (IC) 2 is bonded to the package 4, the space is disposed betweenthe inner surface of the package 8 and the package 4, and the space isdisposed between the inner surface of the package 8 and the integratedcircuit (IC) 2. Thus, the heat generated in the integrated circuit (IC)2 is conducted to the resonator element 3 in a short period of time, andthus the temperature difference between the integrated circuit (IC) 2and the resonator element 3 is made small. As a result, the error intemperature compensation by the temperature compensation circuit 40decreases, and thus, the superior wander performance described above canbe realized.

In the oscillator 1, the package 4 has the base 4 a, and the lid 4 b forsealing the base 4 a and having the metallic material, and theintegrated circuit (IC) 2 is bonded to the lid 4 b. Since the materialof the lid 4 b to which the integrated circuit (IC) 2 is bonded is metalhigh in thermal conductivity, the heat generated in the integratedcircuit (IC) 2 is conducted to the resonator element 3 in a short periodof time to decrease the temperature difference between the integratedcircuit (IC) 2 and the resonator element 3. As a result, in theoscillator 1, the error in temperature compensation by the temperaturecompensation circuit 40 decreases, and thus, the superior wanderperformance described above can be realized.

1.4. Modified Examples of Oscillator

Then, some modified examples of the oscillator according to the presentembodiment will be described.

1.4.1. First Modified Example

FIG. 13 is a plan view schematically showing the base 4 a of the package4 of an oscillator according to a first modified example. FIG. 13corresponds to FIG. 5.

As shown in FIG. 13, in the oscillator according to the first modifiedexample, the arrangement of the electrode pads 11 a, 11 b, the electrodepads 13 a, 13 b, and the extraction interconnections 14 a, 14 b disposedon the base 4 a is different from the arrangement shown in FIG. 5described above.

As shown in FIG. 13, in a planar view (viewed from the normal directionof the bottom surface of the base 4 a), when drawing an imaginarystraight line L passing through the center of the base 4 a to divide thebase 4 a into two equal parts, the electrode pad 13 a and the electrodepad 13 b are located in the part where the electrode pad 11 a and theelectrode pad 11 b are disposed. Therefore, the difference in lengthbetween the extraction interconnection 14 a and the extractioninterconnection 14 b can be made smaller compared to the arrangementshown in FIG. 5. In the example shown in the drawing, the length of theextraction interconnection 14 a and the length of the extractioninterconnection 14 b are equal to each other.

In the oscillator according to the first modified example, when drawingthe imaginary straight line L passing through the center of the base 4 ato divide the base 4 a into two equal parts in the planar view, theelectrode pad 13 a and the electrode pad 13 b are located in the partwhere the electrode pad 11 a and the electrode pad 11 b are disposed.Therefore, it is possible to decrease the difference between the lengthof the extraction interconnection 14 a and the length of the extractioninterconnection 14 b. Thus, it is possible to decrease the differencebetween the path length of the path through which the heat from theoutside of the package 4 is transferred to the resonator element 3 viathe electrode pad 13 a, the extraction interconnection 14 a and theelectrode pad 11 a, and the path length of the path through which theheat is transferred to the resonator element 3 via the electrode pad 13b, the extraction interconnection 14 b and the electrode pad 11 b.

As a result, compared to the example of the oscillator 1 shown in FIG. 5described above, for example, the temperature variation of the resonatorelement 3 can be reduced, and thus, the temperature difference betweenthe integrated circuit (IC) 2 and the resonator element 3 can further bedecreased. Therefore, according to the first modified example, it ispossible to realize the oscillator having the wander performancesuperior to the wander performance of the oscillator 1 shown in FIG. 11and FIG. 12 described above.

1.4.2. Second Modified Example

Although in the embodiment described above, the space of the package 4for housing the resonator element 3 and the space of the package 8 forhousing the integrated circuit (IC) 2 and the package 4 are providedwith the nitrogen gas atmosphere, it is also possible to provide thesespaces with a helium gas atmosphere. Since the helium gas is higher inthermal conductivity compared to the nitrogen gas, the temperaturedifference between the integrated circuit (IC) 2 and the resonatorelement 3 can further be decreased. As a result, according to thepresent modified example, it is possible to realize the oscillatorhaving the wander performance superior to the wander performance of theoscillator 1 shown in FIG. 11 and FIG. 12 described above.

Further, it is also possible to arrange that the space of the package 4for housing the resonator element 3 is provided with the inert gasatmosphere such as the nitrogen gas, or the helium gas, and the space ofthe package 8 (the space for housing the integrated circuit (IC) 2 andthe package 4) is in the vacuum state (the state in which the pressureis lower than the atmospheric pressure). Thus, it is possible to reducethe influence of the temperature variation outside the package 8 on theintegrated circuit (IC) 2 and the resonator element 3 while decreasingthe temperature difference between the integrated circuit (IC) 2 and theresonator element 3. As a result, according to the present modifiedexample, it is possible to realize the oscillator having the wanderperformance superior to the wander performance of the oscillator 1 shownin FIG. 11 and FIG. 12 described above.

2. Electronic Apparatus

FIG. 14 is a functional block diagram showing an example of aconfiguration of an electronic apparatus according to the presentembodiment. Further, FIG. 15 is a diagram showing an example of theappearance of a smartphone as an example of the electronic apparatusaccording to the present embodiment.

The electronic apparatus 300 according to the present embodiment isconfigured including an oscillator 310, a central processing unit (CPU)320, an operation section 330, a read only memory (ROM) 340, a randomaccess memory (RAM) 350, a communication section 360, and a displaysection 370. It should be noted that the electronic apparatus accordingto the present embodiment can be provided with a configuration obtainedby eliminating or modifying some of the constituents (sections) shown inFIG. 14, or adding other constituents thereto.

The oscillator 310 is provided with an integrated circuit (IC) 312 and aresonator 313. The integrated circuit (IC) 312 oscillates the resonator313 to generate an oscillation signal. The oscillation signal is outputfrom an external terminal of the oscillator 310 to the CPU 320.

The CPU 320 performs a variety of types of arithmetic processing andcontrol processing using the oscillation signal input from theoscillator 310 as a clock signal in accordance with the program storedin the ROM 340 and so on. Specifically, the CPU 320 performs a varietyof processes corresponding to the operation signal from the operationsection 330, a process of controlling the communication section 360 forperforming data communication with external devices, a process oftransmitting a display signal for making the display section 370 displaya variety of types of information, and so on.

The operation section 330 is an input device constituted by operationkeys, button switches, and so on, and outputs the operation signalcorresponding to the operation by the user to the CPU 320.

The ROM 340 stores the programs, data, and so on for the CPU 320 toperform the variety of types of arithmetic processing and controlprocessing.

The RAM 350 is used as a working area of the CPU 320, and temporarilystores, for example, the programs and the data retrieved from the ROM340, the data input from the operation section 330, and the calculationresult obtained by the CPU 320 performing operations in accordance withthe variety of types of programs.

The communication section 360 performs a variety of types of control forachieving the data communication between the CPU 320 and the externaldevices.

The display section 370 is a display device formed of a liquid crystaldisplay (LCD) or the like, and displays a variety of types ofinformation based on the display signal input from the CPU 320. Thedisplay section 370 can also be provided with a touch panel, whichfunctions as the operation section 330.

By applying, for example, the oscillator 1 described above as theoscillator 310, it is possible to realize the electronic apparatusequipped with the oscillator having an excellent wander performance evenin the severe temperature environment.

As such an electronic apparatus 300, a variety of electronic apparatusescan be adopted, and there can be cited, for example, a personal computer(e.g., a mobile type personal computer, a laptop personal computer, anda tablet personal computer), a mobile terminal such as a smartphone or acellular phone, a digital camera, an inkjet ejection device (e.g., aninkjet printer), a storage area network apparatus such as a router oraswitch, a local area network apparatus, an apparatus for a mobileterminal base station, a television set, a video camera, a videocassette recorder, a car navigation system, a real-time clock device, apager, a personal digital assistance (including one having acommunication function), an electronic dictionary, an electroniccalculator, an electronic game machine, a gaming controller, a wordprocessor, a workstation, a picture phone, a security televisionmonitor, electronic binoculars, a POS terminal, a medical instrument(e.g., an electronic thermometer, a blood pressure monitor, a bloodglucose monitor, an electrocardiograph, ultrasonic diagnostic equipment,and an electronic endoscope), a fish finder, a variety of measuringinstruments, gauges (e.g., gauges for cars, aircrafts, and boats andships), a flight simulator, a head-mount display, a motion tracer, amotion tracker, a motion controller, and a pedestrian dead reckoning(PDR) system.

As an example of the electronic apparatus 300 according to the presentembodiment, there can be cited a transmission device using theoscillator 310 described above as a reference signal source, avoltage-controlled oscillator (VCO), or the like, and functioning as,for example, a terminal base station device for performing communicationwith terminals wirelessly or with wire. By applying the oscillator asthe oscillator 310, it is possible to realize the electronic apparatus,for which the high performance and the high reliability are required,and which is available for, for example, the communication base station.

Further, as another example of the electronic apparatus 300 according tothe present embodiment, it is possible to adopt a communication devicein which the communication section 360 receives an external clocksignal, and the CPU 320 (the processing section) includes a frequencycontrol section for controlling the frequency of the oscillator 310based on the external clock signal and the output signal (an internalclock signal) of the oscillator 310. The communication device can be acommunication apparatus used for, for example, a backbone networkapparatus such as Stratum-3, or a femtocell.

3. Vehicle

FIG. 16 is a diagram (a top view) showing an example of a vehicleaccording to the present embodiment. The vehicle 400 shown in FIG. 16 isconfigured including an oscillator 410, controllers 420, 430, and 440for performing a variety of types of control such as an engine system, abrake system, and a keyless entry system, a battery 450, and a backupbattery 460. It should be noted that the vehicle according to thepresent embodiment can have a configuration obtained by eliminating someof the constituents (sections) shown in FIG. 16, or adding otherconstituents thereto.

The oscillator 410 is provided with an integrated circuit (IC) and aresonator element not shown, and the integrated circuit (IC) oscillatesthe resonator element to generate the oscillation signal. Theoscillation signal is output from the external terminal of theoscillator 410 to the controllers 420, 430, and 440, and is used as, forexample, a clock signal.

The battery 450 supplies the oscillator 410 and the controllers 420,430, and 440 with electrical power. The backup battery 460 supplies theoscillator 410 and the controllers 420, 430, and 440 with the electricalpower when the output voltage of the battery 450 drops to a level lowerthan a threshold value.

By applying, for example, the oscillator 1 described above as theoscillator 410, it is possible to realize the vehicle equipped with theoscillator having an excellent wander performance even in the severetemperature environment.

As such a vehicle 400, there can be adopted a variety of types ofvehicles, and there can be cited a car (including an electric car), anaircraft such as a jet plane ora helicopter, a ship, a boat, a rocket,an artificial satellite, and so on.

The invention is not limited to the embodiment, but can be implementedwith a variety of modifications within the scope or the spirit of theinvention.

The embodiment and the modified examples described above areillustrative only, and the invention is not limited to the embodimentand the modified examples. For example, it is also possible toarbitrarily combine any of the embodiment and the modified examplesdescribed above with each other.

The invention includes configurations (e.g., configurations having thesame function, the same way, and the same result, or configurationshaving the same object and the same advantage) substantially the same asthe configuration described as the embodiment of the invention. Further,the invention includes configurations obtained by replacing anon-essential part of the configuration described as the embodiment ofthe invention. Further, the invention includes configurations providingthe same functions and advantages and configurations capable ofachieving the same object as the configuration described as theembodiment of the invention. Further, the invention includesconfigurations obtained by adding known technologies to theconfiguration described as one of the embodiments of the invention.

The entire disclosure of Japanese Patent Application No.2016-055870,filed Mar. 18, 2016 is expressly incorporated by reference herein.

What is claimed is:
 1. A temperature-compensated oscillator comprising:a resonator element; an oscillating circuit; and a temperaturecompensation circuit, wherein in a case of varying temperature in atemperature range of ±5° C. centered on a reference temperature inintervals of 6 minutes, and assuming observation period as τ, a wanderperformance fulfills a condition that an MTIE value is equal to orshorter than 6 ns in a range of 0 s<τ≦0.1 s, the MTIE value is equal toor shorter than 27 ns in a range of 0.1 s<τ≦1 s, the MTIE value is equalto or shorter than 250 ns in a range of 1 s<τ≦10 s, the MTIE value isequal to or shorter than 1700 ns in a range of 10 s<τ≦100 s, and theMTIE value is equal to or shorter than 6332 ns in a range of 100s<τ≦1000 s.
 2. The oscillator according to claim 1, wherein in a case ofkeeping the temperature constant at the reference temperature, thewander performance fulfills a condition that the MTIE value is equal toor shorter than 15 ns in the range of 0.1 s<τ≦1 s, the MTIE value isequal to or shorter than 23 ns in the range of 1 s<τ≦10 s, the MTIEvalue is equal to or shorter than 100 ns in the range of 10 s<τ≦100 s,and the MTIE value is equal to or shorter than 700 ns in the range of100 s<τ≦1000 s.
 3. The oscillator according to claim 1, furthercomprising: a first container housing the resonator element; anelectronic component provided with the oscillating circuit and thetemperature-compensation circuit; and a second container housing thefirst container and the electronic component, wherein the electroniccomponent is bonded to the first container, a space is disposed betweenan inner surface of the second container and the first container, and aspace is disposed between an inner surface of the second container andthe electronic component.
 4. The oscillator according to claim 2,further comprising: a first container housing the resonator element; anelectronic component provided with the oscillating circuit and thetemperature-compensation circuit; and a second container housing thefirst container and the electronic component, wherein the electroniccomponent is bonded to the first container, a space is disposed betweenan inner surface of the second container and the first container, and aspace is disposed between an inner surface of the second container andthe electronic component.
 5. The oscillator according to claim 3,wherein the first container includes a base, and a lid adapted to sealthe base and made of metal, and the electronic component is bonded tothe lid.
 6. The oscillator according to claim 4, wherein the firstcontainer includes a base, and a lid adapted to seal the base and madeof metal, and the electronic component is bonded to the lid.
 7. Theoscillator according to claim 3, wherein the space in the secondcontainer is in a vacuum state.
 8. The oscillator according to claim 4,wherein the space in the second container is in a vacuum state.
 9. Theoscillator according to claim 5, wherein the space in the secondcontainer is in a vacuum state.
 10. The oscillator according to claim 6,wherein the space in the second container is in a vacuum state.
 10. Atemperature-compensated oscillator comprising: a resonator element; anoscillating circuit; and a temperature compensation circuit, wherein ina case of keeping the temperature constant at a reference temperature,the wander performance fulfills a condition that a MTIE value is equalto or shorter than 15 ns in a range of 0.1 s<τ≦1 s, the MTIE value isequal to or shorter than 23 ns in a range of 1 s<τ≦10 s, the MTIE valueis equal to or shorter than 100 ns in a range of 10 s<τ≦100 s, and theMTIE value is equal to or shorter than 700 ns in a range of 100 s<τ≦1000s.
 11. An electronic apparatus comprising: the oscillator according toclaim
 1. 12. An electronic apparatus comprising: the oscillatoraccording to claim
 2. 13. An electronic apparatus comprising: theoscillator according to claim
 3. 14. An electronic apparatus comprising:the oscillator according to claim
 5. 15. An electronic apparatuscomprising: the oscillator according to claim
 10. 16. A vehiclecomprising: the oscillator according to claim
 1. 17. A vehiclecomprising: the oscillator according to claim
 2. 18. A vehiclecomprising: the oscillator according to claim
 3. 19. A vehiclecomprising: the oscillator according to claim
 5. 20. A vehiclecomprising: the oscillator according to claim 10.